The ADEME carbon base defines the carbon contents for the most common goods and services, simply register with ADEME as a user on www.basecarbone.fr
The examples given here are all from there. Globally, the ISO14067 standard unifies the calculations.
ADEME is the French national reference body for energy management and climate protection, it publishes the best carbon content databases, the www.basecarbone.fr for all products and services, and https://www.inies.fr/accueil/ for building materials and techniques.
Even more simplified: you can answer 6 questions and thus assume your carbon footprint: EMPRAPID
For quick carbon footprint calculation, you can also check the numbers and add them in the leaf simple below (possible in PDF)